Show better error message when accessing React APIs on React Native

Libraries/Utilities/throwOnWrongReactAPI.js

@@ -0,0 +1,32 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @providesModule throwOnWrongReactAPI
+ * @flow
+ */
+
+'use strict';
+
+function throwOnWrongReactAPI(key: string) {
+  throw new Error(
+`Seems you're trying to access 'ReactNative.${key}' from the 'react-native' package. Perhaps you meant to access 'React.${key}' from the 'react' package instead?
+
+For example, instead of:
+
+  import React, { Component, View } from 'react-native';
+
+You should now do:
+
+  import React, { Component } from 'react';
+  import { View } from 'react-native';
+
+Check the release notes on how to upgrade your code - https://github.com/facebook/react-native/releases/tag/v0.25.1
+`);
+}
+
+module.exports = throwOnWrongReactAPI;

Libraries/react-native/react-native.js

@@ -174,6 +174,20 @@ const ReactNative = {
   },
 };
 
+// Better error messages when accessing React APIs on ReactNative
+if (__DEV__) {
+  const throwOnWrongReactAPI = require('throwOnWrongReactAPI');
+  const reactAPIs = [ 'createClass', 'Component' ];
+
+  for (const key of reactAPIs) {
+    Object.defineProperty(ReactNative, key, {
+      get() { throwOnWrongReactAPI(key); },
+      enumerable: false,
+      configurable: false
+    });
+  }
+}
+
 // Preserve getters with warnings on the internal ReactNative copy without
 // invoking them.
 const ReactNativeInternal = require('ReactNative');